Clutch

Abstract

A clutch includes: a rotor that has a steel material as a base material and is rotated upon receiving a rotational drive force from a drive source; and an armature that has a steel material as a base material and receives the rotational drive force from the rotor when the armature is attracted to the rotor by a magnetic force. The armature has a contact surface side region that includes a contact surface, which contacts a counterpart when the armature is attracted to the rotor. The contact surface side region has a plurality of pores opened at the contact surface and forms a nitride compound of an element of the base material through nitridization of a part of the base material while the contact surface side region is harder than an unreacted portion of the base material that is not reacted at the nitridization.

1 . A clutch comprising:
 a rotor that has a steel material as a base material of the rotor, wherein the rotor is rotated when the rotor receives a rotational drive force from a drive source; and   an armature that has a steel material as a base material of the armature, wherein the rotational drive force is conducted to the armature when the armature is attracted to and is engaged with the rotor by a magnetic force, wherein:   the armature includes a contact surface side region that includes a contact surface, which contacts a counterpart when the armature is attracted to and is engaged with the rotor;   the contact surface side region includes a plurality of pores that open at the contact surface, wherein a nitride compound of an element of the base material of the armature is formed at the contact surface side region through nitridization of a portion of the base material of the armature while the contact surface side region is harder than an unreacted portion of the base material of the armature, which is unreacted at the nitridization; and   the plurality of pores is capable of receiving and holding powder, which is generated by abrasion of the contact surface side region through engagement and disengagement between the rotor and the armature.   
     
     
         2 . A clutch comprising:
 a rotor that has a steel material as a base material of the rotor, wherein the rotor is rotated when the rotor receives a rotational drive force from a drive source; and   an armature that has a steel material as a base material of the armature, wherein the rotational drive force is conducted to the armature when the armature is attracted to and is engaged with the rotor by a magnetic force, wherein:   the armature includes a contact surface side region that includes a contact surface, which contacts a counterpart when the armature is attracted to and is engaged with the rotor;   the contact surface side region includes a plurality of pores that open at the contact surface, wherein a nitride compound of an element of the base material of the armature is formed at the contact surface side region while the contact surface side region is harder than the base material of the armature; and   the plurality of pores is capable of receiving and holding powder, which is generated by abrasion of the contact surface side region through engagement and disengagement between the rotor and the armature.   
     
     
         3 . A clutch comprising:
 a rotor that has a steel material as a base material of the rotor, wherein the rotor is rotated when the rotor receives a rotational drive force from a drive source; and   an armature that has a steel material as a base material of the armature, wherein the rotational drive force is conducted to the armature when the armature is attracted to and is engaged with the rotor by a magnetic force, wherein:   the rotor includes a contact surface side region that includes a contact surface, which contacts a counterpart when the armature is attracted to and is engaged with the rotor; and   the contact surface side region includes a plurality of pores that open at the contact surface, wherein a nitride compound of an element of the base material of the rotor is formed at the contact surface side region through nitridization of a portion of the base material of the rotor while the contact surface side region is harder than an unreacted portion of the base material of the rotor, which is unreacted at the nitridization; and   the plurality of pores is capable of receiving and holding powder, which is generated by abrasion of the contact surface side region through engagement and disengagement between the rotor and the armature.   
     
     
         4 . A clutch comprising:
 a rotor that has a steel material as a base material of the rotor, wherein the rotor is rotated when the rotor receives a rotational drive force from a drive source; and   an armature that has a steel material as a base material of the armature, wherein the rotational drive force is conducted to the armature when the armature is attracted to and is engaged with the rotor by a magnetic force, wherein:   the rotor includes a contact surface side region that includes a contact surface, which contacts a counterpart when the armature is attracted to and is engaged with the rotor; and   the contact surface side region includes a plurality of pores that open at the contact surface, wherein a nitride compound of an element of the base material of the rotor is formed at the contact surface side region while the contact surface side region is harder than the base material of the rotor; and   the plurality of pores is capable of receiving and holding powder, which is generated by abrasion of the contact surface side region through engagement and disengagement between the rotor and the armature.   
     
     
         5 . The clutch according to  claim 1 , wherein the contact surface side region has a thickness that is equal to or larger than 2 μm and is equal to or smaller than 10 μm. 
     
     
         6 . (canceled) 
     
     
         7 . A manufacturing method of a clutch that includes:
 a rotor that has a steel material as a base material of the rotor, wherein the rotor is rotated when the rotor receives a rotational drive force from a drive source; and   an armature that has a steel material as a base material of the armature, wherein the rotational drive force is conducted to the armature when the armature is attracted to and is engaged with the rotor by a magnetic force, the manufacturing method comprising:   a processing step of forming the armature, which includes a contact surface that contacts a counterpart when the armature is attracted to and is engaged with the rotor, by applying a mechanical process to the base material of the armature;   a nitrocarburizing step of forming a contact surface side region, which is harder than the base material of the armature and includes a plurality of pores that open at the contact surface, by applying a nitrocarburizing process to at least the contact surface of the armature after the processing step; and   an anti-rust step of forming an anti-rust film by applying an anti-rust process to a region at a surface of the armature, which is other than at least the contact surface after the nitrocarburizing step, wherein the plurality of pores is capable of receiving and holding powder, which is generated by abrasion of the contact surface side region through engagement and disengagement between the rotor and the armature.   
     
     
         8 . The manufacturing method of the clutch according to  claim 7 , wherein the processing step includes a finishing step of forming the contact surface of the armature by cutting a surface of the base material, which is press formed into a shape of the armature. 
     
     
         9 . A manufacturing method of a clutch that includes:
 a rotor that has a steel material as a base material of the rotor, wherein the rotor is rotated when the rotor receives a rotational drive force from a drive source; and   an armature that has a steel material as a base material of the armature, wherein the rotational drive force is conducted to the armature when the armature is attracted to and is engaged with the rotor by a magnetic force, the manufacturing method comprising:   a processing step of forming the rotor, which includes a contact surface that contacts a counterpart when the armature is attracted to and is engaged with the rotor, by applying a mechanical process to the base material of the rotor;   a nitrocarburizing step of forming a contact surface side region, which is harder than the base material of the rotor and includes a plurality of pores that open at the contact surface, by applying a nitrocarburizing process to at least the contact surface of the rotor after the processing step; and   an anti-rust step of forming an anti-rust film by applying an anti-rust process to a region at a surface of the rotor, which is other than at least the contact surface after the nitrocarburizing step, wherein the plurality of pores is capable of receiving and holding powder, which is generated by abrasion of the contact surface side region through engagement and disengagement between the rotor and the armature.   
     
     
         10 . The manufacturing method of the clutch according to  claim 9 , wherein the processing step includes a finishing step of forming the contact surface of the rotor by cutting a surface of the base material, which is press formed into a shape of the rotor. 
     
     
         11 . (canceled)